Device and method for roll forming profiles with changeable cross-section

ABSTRACT

The invention relates to a device for bending flat semi-finished products into a profile having a changeable cross-section along the length thereof˜comprising at least one roll stand having profiling units in form of rollers and/or matrices. The semi-finished product can be led lengthwise between the profiling units. The invention further comprises at least two linear actuators ( 10, 12, 14, 16 ), arranged transversely to the length (Z) of the semi-finished product in order to produce translatory movements of the roll stand and rotational movements of the roll stand about an axis (Y) thereof. According to the invention, each of the at least two linear actuators are connected to the roll stand at a point provided at a distance from the axis (Y) of the roll stand.

The invention refers to a device and a method according to the preambles of the independent patent claims.

Such a device with which profiles with variable cross-sections can be produced by adjusting pairs of rolls with a translational and a rotational movement, is known from DE 100 11 755 A1. A similar device having an additional roll and a supporting element for a flange formed on the semi-finished product is known from DE 10 2004 040 257 A1.

In the device known from DE 100 11 755 A1 and the method carried out with it, the translational movement and the rotational movement are largely produced independently from one another. The drawback of this solution is that the linear actuator responsible for the translational movement has to perform the entire advancement operation by itself if a translational movement only is produced and that the linear actuator responsible for the rotational movement has to perform the entire torsion operation by itself if a rotational movement only is produced. Therefore, the two linear actuators taken together must be made larger, both in terms of performance and in terms of dimensions, than would be necessary to achieve the overall performance required during operation.

The object underlying the invention is to enable roll forming of cold or hot profiles with variable cross-section by means of rolls and dies with drives having lower performance and less space occupation.

This object is solved in a device of the above outlined type and in the corresponding method by the characterizing features of the independent patent claims.

As contrasting to the device known from DE 100 11 755 A1 where the linear actuator responsible for the translational movement extends along the connection line between the support of the linear actuator, the support being fixed to the machine, and the rotational axis of the roll stand, each of the at least two linear actuators in this invention is articulated to the roll stand in a position provided at a distance from the rotational axis of the roll stand. In other words, both a translation-only movement and a rotation-only movement of the roll stand are produced by the at least two linear actuators in common. In this manner, advancement operations and torsional operations are divided among the two linear actuators, namely particularly evenly during the translation-only and rotation-only movements of the roll stand which are frequently required. Therefore, the linear actuators can be substantially lower in performance and more compact than those of the well-known bending devices.

Advantageous further developments of the invention are disclosed in the dependent claims.

Subsequently there is enclosed a description of embodiments of the invention by means of the figures wherein:

FIG. 1 shows an adjustment stand for a roll stand for roll forming of cold and hot profiles with variable cross-sections,

FIG. 2 shows four schematic drawings of variants and further developments of the adjustment stand shown in FIG. 1, and

FIG. 3 shows another embodiment of an adjustment stand.

The adjustment stand shown perspectively in FIG. 1 has an oblong rectangular bottom plate 2 with two linear guide rails 4 which extend along the lateral edges of the bottom plate 2. A carriage 6 is mounted slidably on the two linear guide rails 4, i. e. the carriage 6 is mounted slidably on the bottom plate 2 in the X direction of the indicated Cartesian coordinate system. In the center of the carriage 6, a base plate 8 of a roll stand (not shown) is rotatably mounted, which base plate is circular in this embodiment, but can basically be of any shape; i. e. the base plate 8 is mounted rotatably in the Y direction.

The roll stand fastened to the base plate 8 is of a type as described in the publications DE 100 11 755 A1 and DE 10 2004 040 257 A1 mentioned above and contains roll forming devices such as rolls and/or matrices. A profile or semi-finished product to be processed is fed in in the Z direction in FIG. 1 and advanced and is provided with a variable cross-section by adjustment of the roll stand in the X direction and about the Y axis, wherein the profile can be bent cold or hot.

One threaded spindle 10 each extends in a parallel direction to each linear guide rail 4 and above the carriage 6, the ends of which threaded spindle are mounted in bearing blocks fastened to the bottom plate 2. One end of each threaded spindle 10 is axially coupled to a unit 12 consisting of an electric motor and a transmission, which unit is fastened to one of the bearing blocks and will be simply called drive motor in the following. The two drive motors 12 protrude over the bottom plate 2 in the X direction and are arranged next to each other with axes parallel to the X direction.

In addition to the bottom plate 2, an auxiliary carriage 14 is also mounted slidably on each of the two linear guide rails 4, each threaded spindle 10 engaging a nut fastened to the corresponding carriage 14 or a female thread formed inside it. A push rod 16 is articulated (i. e. via a hinge or ball joint) to each of the two auxiliary carriages 14, which push rod 16 runs approximately parallel to the neighboring linear guide rail 4 up to a point of the base plate 8 where it is articulated (i. e. via a hinge or ball joint) to the base plate 8. The positions on the base plate 8 marked by small circles, where the push rods 16 are coupled to the base plate 8, are opposite to each other radially and equidistant with respect to the axis running in the Y direction (Y axis) of the base plate 8 or the roll stand, respectively.

If the threaded spindles 10 are driven by means of the drive motors 12 with equal speed and in opposite rotational directions, the base plate 8 or the roll stand, respectively, are rotated around the Y axis by means of the push rods 16. If the threaded spindles 10 are driven by means of the drive motors 12 with equal speed and in the same rotational directions, the base plate 8 or the roll stand, respectively, are shifted in the X direction by means of the push rods 16. By choosing the suitable rotational directions and rotational speeds of the drive motors 12, the base plate 8 or the roll stand, respectively, can be subjected to any combination of rotational movements around the Y axis and translational movements in the X direction, i. e. they can be moved with two degrees of freedom in order to provide a semi-finished profile which has just been processed with a variable cross-section.

The substantial forces which occur during forming are distributed over both drives. Both torques and thrusts to be applied are distributed evenly over both drive motors 12 so that they can be dimensioned to be weaker than in conventional adjustment stands. The members for transmitting forces from the drive motors 12 to the base plate 8 can be dimensioned to be weaker as well. The drive motors 12 are arranged so as to be parallel and not included in the movement. This allows for a short distance between roll stands each of which is connected to an adjustment stand as shown in FIG. 1.

FIG. 2 shows perspective schematic drawings of adjustment stands in a Cartesian coordinate system corresponding to FIG. 1. Articulations (e. g. by means of hinge or ball joints) are shown as black dots.

FIG. 2 a shows an adjustment stand similar to the one in FIG. 1, with the linear actuators consisting of the elements 10, 12, 14 and 16 being schematically represented as linear actuators 20, 22 in FIG. 2, each of which actuators having a push rod 20 a, 22 a which can be moved back and forth and engage the base plate 24 of a roll stand (not shown) by means of additional push rods.

FIG. 2 b shows the adjustment stand of FIG. 2 a, extended by a third linear actuator 26 arranged between the linear actuators 20, 22 and parallel thereto, which engages a third contact point on the base plate 24 via an additional push rod 28 which is at approximately an angle of 45 degrees to the Y direction and is slanted to the Y direction in a central position of the adjustment stand, which third linear actuator is spaced from the contact points of the linear actuators 20, 22 and not in one line with them.

In the adjustment stand of FIG. 2 b, the base plate 24 is additionally mounted slidably in the Y direction so that it can be translated in another degree of freedom by means of the third linear actuator 26.

As an alternative, the base plate 24 of the adjustment stand in FIG. 2 b can be pivoted around the Z axis instead of being slidable in the Y direction so that the additional degree of freedom achieved is a degree in freedom of rotation and not of translation.

In spite of this additional functionality, this adjustment stand of FIG. 2 b practically occupies no more space than the adjustment stand of FIG. 2 a, and the forces occurring are distributed over one more drive.

FIG. 2 c shows the adjustment stand of FIG. 2 a, extended by a third and a fourth linear actuator 30, 32 with one additional push rod each which are arranged perpendicular to the linear actuators 20, 22 and engage the base plate 24 in two contact points spaced from the contact points of the linear actuators 20, 22 and opposite to one another radially and equidistant with respect to the axis running in the X direction (X axis) of the base plate 24.

The adjustment stand of FIG. 2 c can be moved in four degrees of freedom by means of the linear actuators 20, 22, 30 and 32. For this purpose, the base plate 24 must be mounted with four degrees of freedom. Instead of with rotary and sliding bearings as in the preceding embodiments, this is achieved much more easily with two additional, fifth and sixth, push rods 34, 36 one end of which is connected to points 38 fixed to the machine and the other end of which engages any points of the roll stand which are not laying in the plane of the base plate 24, e. g. the ends of an axial rod through the base plate 24 as shown schematically in FIG. 2 c.

If these fifth and sixth push rods 34 and 36 are not connected to the points 38 fixed to the machine but to a fifth or sixth linear actuator 40, 42, the embodiment of FIG. 2 d is obtained where the roll stand is movable in six degrees of freedom, three of rotation and three of translation.

Incidentally, the linear actuators and push rods do not have to be arranged in a parallel or a perpendicular direction to one another, as shown in FIG. 2, but with a few exceptions, they can substantially assume any positions in space. The contact points of the linear actuators with the base plate 24 or the roll stand, respectively, can also be substantially any as desired, with a few exceptions.

Incidentally, a positioning system as in FIG. 2 a is called bipod, a positioning system as in FIG. 2 c tripod, a positioning system as in FIG. 2 c tetrapod, and a positioning system as in FIG. 2 d is called hexapod or hexaglide, as is basically known. Additionally, there are also pentapods which can be envisaged as being formed by the substitution of one of the linear actuators in FIG. 2 d by a point fixed on the machine, movements in all spacial directions being possible here as well.

If such positioning systems are applied to a roll stand for roll forming of cold or hot profiles with variable cross-sections by means of rolls or matrices, the fact that the forces acting during operation are distributed over all drives is of special importance. The forces acting or operating on a roll stand are particularly high, and the lower dimensions due to the distribution of forces are especially advantageous here since they make it possible to arrange roll stands very close to one another so that even relatively slender profiles can be provided with variable cross-sections which could up to this point not be roll formed due to expansive adjustment stands.

FIG. 3 shows another embodiment of an adjustment stand which is similar to the adjustment stand in FIG. 1 insofar as it also has an oblong rectangular bottom plate 2′, two linear guide rails 4′ fastened to the bottom plate 2′, a carriage 6′ slidable along the linear guide rails 4′ and a base plate 8′ of a roll stand which is mounted rotatably on the carriage 6′.

Other than in the embodiment in FIG. 1, the linear drives are not formed by a threaded spindle 10, a drive motor 12, an auxiliary carriage 14 and a push rod 16 each, but by a machine element which comprises a bearing block 44 mounted rotatably in the horizontal direction on the bottom plate 2′, a push rod 46 passing through the bearing block 44, which push rod is articulated to one end of the base plate 8′, and a drive motor 48.

The push rod 46 can be a spindle which passes through a spindle nut in the bearing block 44 and is rotated by the drive motor 48 via a countershaft, where the push rod 46 must be articulated rotatably about its own axis to one end of the base plate 8′. The push rod 46 can also be a spindle which is rotated by the drive motor 48 and passes through a spindle nut articulated to the base plate 8′. In such spindle solutions for the push rods 46, naturally the torque that occurs must be supported or induced by the motor, respectively. Alternatively, the push rod 46 can be a rod which is pushed forward and backward by the drive motor 48 in some other way.

In the embodiment in FIG. 3, the linear actuators are therefore machine elements rotatably mounted at both ends which can also be used in the variants and further developments in FIG. 2 by the use of couplings instead of rotary bearings, which couplings are articulated in several dimensions.

In the embodiment in FIG. 3, the two push rods 46 extend precisely parallel to each other only in the particular case where they are deployed to the same length. In other cases, they approach each other in the direction of the base plate 8′. To counteract the resulting reduction in torque at certain rotation angles of the base plate 8, the two bearing blocks 44 could be arranged in the first place at a greater distance or at a smaller distance than is shown in FIG. 3, depending on which torque characteristics are best suited to the case of application. In the embodiments described above as well, it is not necessary for the linear actuators or two linear actuators or any elements of the linear actuators to be precisely parallel, although this would simplify the construction and control.

Depending on the case of application, it can also be considered to not articulate the linear actuators in diametrically opposed positions on the base plate, as shown in the embodiments, but in positions of other angles than 180° to the rotational axis of the base plate, which may also be arranged at different distances from the rotation axis of the base plate. In this manner as well, certain desired torque characteristics can be obtained.

Neither do the linear actuators have to run orthogonally to the rotational axis of the roll stand. In some applications, a more or less slanted arrangement of the linear actuators to the rotational axis of the roll stand can be useful as well.

The invention is not limited to the embodiments described above. The driving operation can take place electrically, hydraulically, pneumatically and/or mechanically by means of electric motors, linear motors, hydraulic cylinders, hydraulic motors, pneumatic motors or electric cylinders (electric drive with no torque acting on the exterior). For instance, mechanical drives can be implemented with threaded spindles, ball screws, racks, swivel actuators, wind around drives, cylinders/pistons and other power transmission elements.

If technical features mentioned in any claim are designated by reference numbers, these reference numbers have been merely included to increase comprehensibility of the claims. Accordingly, these reference numbers have no limiting effect on the scope of each element which is designated by way of example by such reference numbers. 

1. A device for bending flat semi-finished products into a profile having a variable cross-section along the length thereof, with at least one roll stand with profiling units in the form of rollers and/or matrices between which the semi-finished product can be passed through lengthwise, and having at least two linear actuators, the at least two present linear actuators being arranged in order to produce translatory movements of the at least one roll stand transversely to the length of the semi-finished product and rotational movements of the at least one roll stand about an axis thereof, wherein each of the at least two present linear actuators is articulated to the roll stand at a position provided at a distance from the axis.
 2. The device according to claim 1, wherein the linear actuators are provided in pairs, the linear actuators of a pair being arranged parallel or substantially parallel to each other.
 3. The device according to claim 1, wherein the at least two present linear actuators have linear drives which engage in positions on the roll stand that are substantially opposite to each other with respect to the axis of the roll stand, via push rods articulated at both ends.
 4. The device according to claim 1, wherein each linear actuator has a threaded spindle with a motor for rotating the same, a carriage slidable on a linear guide along the threaded spindle and in engagement therewith, and a push rod one end of which is articulated to the carriage and the other end of which is articulated to the position on the roll stand which is engaged by the linear actuator.
 5. The device according to claim 1, wherein the at least two present linear actuators are articulated and supported by a bottom plate of the device.
 6. The device according to claim 4, wherein the roll stand has a base plate extending in a parallel direction to a bottom plate on which the linear actuators are disposed and which is mounted rotatably about its center axis and slidably parallel to the linear actuators, the positions on the roll stand that are engaged by the linear actuators being diametrically opposed positions on the base plate with respect to the center axis of the base plate.
 7. The device according to claim 1, wherein additionally to the at least two present linear actuators, another linear actuator for producing a translational movement of the roll stand in a direction different from the translational movement in claim 1, or a rotational movement of the roll stand in a direction different from the rotational movement in claim 1, is provided.
 8. The device according to claim 7, wherein the additional linear actuator is arranged parallel or substantially parallel to the at least two present linear actuators.
 9. The device according to claim 1, wherein a total of four linear actuators for translation and rotation of the roll stand in four degrees of freedom are provided, the roll stand being coupled to points fixed to the machine via two push rods.
 10. The device according to claim 1, wherein a total of six linear actuators for translation and rotation of the roll stand in six degrees of freedom are provided.
 11. The device according to claim 1, wherein the linear actuators each have a threaded spindle, a hydraulic cylinder or a linear motor.
 12. A method for roll forming flat semi-finished products into a profile having a variable cross-section along the length thereof, the semi-finished product passing lengthwise between profiling units in the form of rollers and/or matrices, each of which is attached to at least one roll stand, which roll stand is shifted during roll forming by at least two linear actuators translatorily transversely to the length (Z) of the semi-finished product and rotatorily about an axis of the roll stand, wherein both a translation-only movement and a rotation-only movement of the roll stand are produced by the at least two present linear actuators in common.
 13. The method according to claim 12, wherein the at least one roll stand is moved in n degrees of freedom by means of n (n=1, 2, . . . , 6) linear actuators. 